Sunday's wildfire near Birdseye Road northwest of Helena was caused by a controlled burn that escaped, Lewis and Clark County Sheriff Leo Dutton said.
The fire remains under investigation and no charges have been filed yet, he said.
Several homes were evacuated and some roads were closed as the fast-moving wildfire burned in the area Sunday afternoon, but all residents were allowed to return home later the same evening.
The fire was reported just before 1:45 p.m. Sunday and burned a total of 9.9 acres, said Birdseye Volunteer Fire Department Chief Kyle Sturgill-Simon. No structures were burned and no injuries were reported, he said.
Firefighters battled windy conditions Sunday afternoon before a snowstorm moved into the area Monday morning. The National Weather Service in Great Falls had issued a warning about high fire danger over the weekend but stopped short of declaring a red flag warning, as wind gusts were localized to certain areas.
"There were concerns about some shifting weather that thankfully didn't come around," Sturgill-Simon said.
He also said the assistance from other departments helped keep the fire from growing. Two helicopters from the Montana Department of Natural Resources and Conservation and personnel from seven volunteer fire departments and the county sheriff's office responded to the fire, and some of them remained on the scene overnight.
"This is the time of year when we start to remind people that fuels near their homes very easily catch embers and can make it a lot harder to defend their homes during a wildfire," Sturgill-Simon said.
Editor Jesse Chaney can be reached at 406-447-4074, or find him on Twitter: @IR_JesseChaney.